1. Field of the Invention
The present invention relates to a slider fastener stringer with a warp-knit stringer tape made of synthetic fibers.
2. Prior Art
There have been proposed a variety of slide fastener stringers having warp-knit stringer tapes of synthetic fibers supporting coupling elements thereon. The warp-knit stringer tapes, however, give a greater amount of resistance to the penetration of a sewing needle when sewn to garments than woven stringer tapes. The warp-knit stringer tapes while they are being attached tend to shrink due to displacement and distortion of stitches where the sewing threads pass through, causing the tape edge on which the coupling elements are mounted to get wavy or puckered. Such problems can be avoided by making a central portion of the warp-knit tape where the sewing needle penetrates structurally coarser than the remainder of the tape, to thereby ease the passing of the needle through the tape.
Another problem with the warp-knit stringer tape is that since the tape is knit of multifilaments of synthetic fiber with a view to minimizing the stretch of both warpwise and coursewise directions, the surfaces of the tape are relatively hard and slippery, allowing the tape to slip or shift on the garment on a sewing machine. The tape thus can be mounted out of place and wrinkly. One solution to such slippage has been to include in the tape two different kinds of inlaid wefts, one made of textured yarns and the other of synthetic fibers of high shrinkability, the textured yarns being bulged on a flat surface of the tape by the shrinkage of the synthetic fiber wefts so as to increase a coefficient of friction of the tape as it is held against the garment during sewing operation. The addition of such different inlaid wefts, however, necessarily results in a thickened central tape portion, which will give rise to an increased degree of resistance to the penetration therethrough of a sewing needle.